Radiation Response of 64k-Bit and 128k-Bit Ultraviolet Erasable Programmable Read Only Memories (UVEPROMs)

The radiation response of 64k-bit and 128k-bit UVEPROMs was tested in a dose-rate and total-dose environment to determine their ability to survive a nuclear event and to be used as a bootstrap-reinitialization firmware following a circumvention cycle. A sample of five 64k-bit UVEPROMs experienced no erasure at dose-rates ranging from 3 × 107 rad(si)/second to 3 × 1010 rad(si)/second. They experienced transient upsets (soft errors) caused by the peripheral address and read circuits in that range of dose-rates. A total of 22 samples of 64k-and 128k-bit UVEPROMs experienced total-dose induced failures at levels ranging from 7 to 14 krad(si). This series of radiation tests confirms the improvement in radiation hardness which has been previously reported for UVEPROM[1]. This improvement is primarily attributable to thinner gate oxides resulting from a finer control of the manufacturing process. Further improvement is expected with the scaled-down geometries of the 256k-bit UVEPROMs not yet available. The relatively widespread distribution of total-dose hardness observed in the UVEPROM testing calls for hardness assurance controls to be exercised by the user in radiation-hard applications.